The present invention relates to an electric component cooling apparatus for cooling an electronic component such as an MPU or the like, and more particularly to an electronic component cooling apparatus of the type that a heat sink on which an electronic component is mounted is forcibly cooled by air fed from a fan unit.
As shown in FIG. 6, an electronic component cooling apparatus disclosed in Japanese Patent Application Laid-Open Publication No. 102787/2001 comprises a heat sink 102 having a plurality of radiation fins 101, a fan unit 105 including an impeller 103 driven by a motor and a casing 104, and casing mounting means 106 located at opposite sides of the casing 104. The casing mounting means 106 are provided to mount the casing 104 on the heat sink 102 so that a gap is provided between the leading ends of the radiation fins 101 and an opposite wall 104a of the casing 104. Air discharged from the impeller 103 passes through the gap formed between the leading ends of the radiation fins 101 and the opposite wall 104a and through intervals between the radiation fins 101 in the heat sink 102, and then flows out to the outside of the casing 104 and the heat sink 102. The electronic component 108 mounted on a base 102a is thereby cooled. The electronic component cooling apparatus is mounted on a circuit board 100 using mounting tools of various structures. Recently, a mounting tool such as a mounting tool 107, indicated by a dotted line in FIG. 6, has also been conceived. In this example, a pushing force toward the heat sink 102 is applied to the opposite wall 104a of the casing 104 to push the base 102a of the heat sink 102 against the electronic component 108, thereby mounting the electronic component cooling device on the circuit board 100.
In this conventional electronic component cooling apparatus, however, a pushing force applied by the mounting tool 107 is exerted on the base 102a through the casing mounting means 106 located on the opposite sides of the casing 104. In this case, a force exerted on the electronic component 108, based on the pushing force locally becomes larger or becomes unbalanced. In this case, for example, a large force is locally applied to an upper corner 108a of the electronic component 108. For this reason, unbalanced contact occurs between the electronic component 108 and the base 102a of the heat sink 102, so that heat dissipation from the electronic component 108 becomes locally unbalanced, and the heat dissipation effect of the electronic component might be thereby reduced.
The present invention has been made in view of the foregoing disadvantage of the prior art.
Accordingly, it is an object of the present invention to provide an electronic component cooling apparatus that can prevent a reduction in the heat dissipation effect of an electronic component when a pushing force toward a heat sink is exerted on the opposite wall of a casing.
It is another object of the present invention to provide an electronic component cooling apparatus that can prevent extreme unbalance in contact between the base of a heat sink and an electronic component when a pushing force toward the heat sink is exerted on the opposite wall of a casing.
It is a further object of the present invention to provide an electronic component cooling apparatus that does not extremely increase air resistance against air that passes through a gap formed between the opposite wall of a casing and a plurality of radiation fins in a heat sink.
In accordance with the present invention, an electronic component cooling apparatus comprises a heat sink, a fan unit, and casing mounting means. The heat sink has a base having a front surface provided thereon with a plurality of radiation fins and a rear surface to be mounted thereon with an electronic component to be cooled. The fan unit includes an impeller having a plurality of blades, a motor for rotating the impeller mounted on a rotor fixedly mounted on a revolving shaft, and a casing having an opposite wall arranged opposite to leading ends of the radiation fins in the heat sink, and an opening for receiving the impeller. The casing mounting means is provided to mount the casing on the heat sink so that the leading ends of the radiation fins are spaced from the opposite wall to define a gap. In this electronic component cooling apparatus, air discharged from the impeller passes through the gap between the heat sink and the leading ends of the radiation fins and through intervals between the radiation fins for discharge to the outside of the casing and the heat sink. Then, when the electronic component cooling apparatus is used, the base of the heat sink is pushed against the electronic component with the pushing force toward the heat sink being applied to a pair of wall sections of the opposite wall located with the opening of the casing interposed therebetween.
In accordance with the present invention, at least one pushing force transferring section for transferring the pushing force to the heat sink through contact with the leading ends of the radiation fins is integrally provided at each of a pair of wall sections of the opposite wall of the casing. Then, at least one pushing force transferring section at each of the pair of wall sections is constructed to distribute the pushing force and transfer distributed force to the heat sink so as to prevent a force applied or transferred to the electronic component by the pushing force from increasing locally and excessively, or being brought into an unbalanced state.
If at least one pushing force transferring section is provided in accordance with the present invention, a pushing force is transferred to the heat sink through the casing mounting means and the pushing force transferring section, with the pushing force toward the hear sink applied to the pair of the wall sections of the opposite wall of the casing. Then, this pushing force is exerted on the electronic component through the heat sink. For this reason, the pushing force is distributed and the distributed force is transferred to the heat sink due to the existence of the pushing force transferring section, so that the force exerted on the electronic component will not increase locally and extremely. In other words, the balanced pushing force is exerted on the entire electronic component, thereby eliminating extreme unbalance in contact between the base of the heat sink and the electronic component. Consequently, an occurrence of local unbalance in heat dissipation of the electronic component can be prevented. A reduction in efficiency of heat dissipation can be thereby prevented.
Preferably, the cross sectional profile or shape of the pushing force transferring section is defined so as to reduce air resistance against the air that passes through the gap between the leading ends of the radiation fins and the opposite wall. This arrangement can streamline the airflow, which would be severely blocked due to the existence of the pushing force transferring section, thereby preventing the cooling effect of the radiation fins from decreasing. In this case, if the cross sectional profile of the pushing force transferring section is formed to have substantially a circular shape, air resistance can be reduced, and the mechanical strength of the pushing force transferring section can be increased.
Further, if an axial fan unit for discharging air in one axial direction of the revolving shaft of the motor is employed as the fan unit, it is preferable that the cross sectional shape of the pushing force transferring section is formed to have an elongate, streamlined shape so that it parallels airflow discharged from the fan unit and then passing through the gap or so that it does not make a large resistance against the airflow. With this arrangement, air resistance of the pushing force transferring section against airflow can be reduced.
Still further, when providing each of pushing force transferring sections for each of the pair of wall sections, it is preferable that the pushing force transferring sections are provided symmetrically on opposite sides of the opening formed in the opposite wall of the casing. With this arrangement, a force exerted on the electronic component becomes symmetrical with respect to the opening, so that the force distributed and then exerted on the electronic component is made to be balanced. Further, since two airflows flowing within the gap in two opposite directions with respect to the opening can be made to be symmetrical, the cooling effects of the radiation fins can be prevented from varying significantly. In order to attain possibly the best balanced contact between the base of the heat sink and the electronic component as well as the force distribution and exertion on the electronic component, the pushing force transferring sections should be respectively formed at the central portions of the pair of the wall sections of the opposite wall.
More particularly, an electronic component cooling apparatus of the present invention comprises a heat sink having a base having a front surface provided thereon with a plurality of radiation fins and a rear surface to be mounted thereon with an electronic component to be cooled, a pair of heat sink side walls being upright from a pair of opposite ends of the base with the radiation fins interposed therebetween, and an axial fan unit. The fan unit includes an impeller having a plurality of blades, a motor for rotating the impeller mounted on a rotor fixedly mounted on a revolving shaft, a casing having an opposite wall arranged opposite to leading ends of the radiation fins in the heat sink with a gap, a pair of casing side walls extending to the heat sink from opposite edges of the opposite wall, and an opening for receiving the impeller and the motor, and a plurality of webs coupling a housing of the motor to the casing so that the motor is positioned at a central portion of the opening. The fan unit further includes casing mounting means for mounting the casing on the heat sink by engagement of engaging sections each provided on the pair of casing side walls with engaged sections each provided on the pair of heat sink side walls. Then, the casing and the heat sink are constructed to form a pair of openings which allow air, discharged from the impeller and passing through the gap and intervals between the radiation fins in the heat sink, to go out of the casing and the heat sink in two opposite directions for discharge. The base in the heat sink is pushed against the electronic component with the pushing force toward the heat sink being applied to a pair of wall sections of the opposite wall located in the two directions with the opening of the casing interposed therebetween. The pushing force transferring sections for transferring the pushing force to the heat sink through contact with the leading ends of the radiation fins are each integrally formed on each of the pair of wall sections of the opposite wall, and the pushing force transferring sections are constructed to distribute the pushing force and transfer distributed force to the heat sink so that a force applied to the electronic component through the casing mounting means, the pushing force transferring sections, and the heat sink based on the pushing force is not so unbalanced as to cause extreme unbalance in contact between the electronic component and the base of the heat sink.